Cassandra Summit 2014: Monitor Everything!

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About Me ●Sr. Engineer at Pythian o Lead of Cassandra Practice #CassandraSummit 2014 ● Remote in Minnesota ● Interests o Java, Clojure, Python dev o Data science o Information Security o Hobbyist electronics

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About Pythian Pythianis a global data outsourcing and consulting company that specializes in optimizing and managing mission-critical data systems. Pythian blends the world’s leading data experts with advanced, secure service delivery processes to create the industry’s best standard of care for its clients. Since its inception, Pythian has managed some of the world’s largest, most business-critical data infrastructures. #CassandraSummit 2014 10,000 Pythian currently manages more than 10,000 systems. 350 Pythian currently employs more than 350 people in 25 countries worldwide. 1997 Pythian was founded in 1997

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About Cassandra ●No Single Point of Failure ● Fault Tolerant ● Awesome properties for an operations team who does not want to get up at 3am #CassandraSummit 2014

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About Cassandra ●Nothing should be set up and forgotten about ● Easy to do with Cassandra though o Fault tolerance on properly configured setup handles single node being down or having temp performance issues o No back pressure on writes until there is a lot of trouble #CassandraSummit 2014

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Utilize the faulttolerance buffer ● Need to observe and react to current issues ● Predict future issues ● Divide this into two approaches #CassandraSummit 2014 o Proactive o Reactive

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Proactive ● Daily& Weekly checkups to prevent, and predict problems o Capacity o Performance bottlenecks o Data Modeling issues #CassandraSummit 2014

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Reactive ● Somethingabout best laid plans… o Hardware failures o Bugs o Malicious or Non-Malicious users ● Alarms, Pager Duty #CassandraSummit 2014

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Common element #CassandraSummit2014 ● Data is needed o form alerts o find anomalies o trending o debugging

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Metrics ● Windowto the application o Bridge the gap - Coda Hale #CassandraSummit 2014

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Gathering Metrics SOURCES Cassandra Environment OpsCenter Logs JMX CPU, Disk, Network Nodetool JVM, GC #CassandraSummit 2014

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Metrics but ofcourse… Without context, the data is just pretty graphs

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JMX ● JavaManagement Extensions ● Complex… very engineered ● Resources represented as objects with attributes and operations ● Used for monitoring or as input #CassandraSummit 2014

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JMX ● Theannoying gateway to metrics ○ Poor tooling - requires java ○ Slow, Memory Leaks ○ Historically and currently frustrating for ops (pre 2.0.8) Cassandra Init connection to port 7199 Reply with hostname:port for 1024-65535 #CassandraSummit 2014 RMI connection Client (You) Gets new hostname:port, drops old connection and attempts to connect 7199 7199 Connected!

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JMX #CassandraSummit 2014 ● Visual o jconsole o visualvm ● Command line o jmxterm o jmxsh ● MX4J ● Jolokia

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JMX [domain]:[key]=[value],[key2]=[value2]... #CassandraSummit2014

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JMX [domain]:[key]=[value],[key2]=[value2]... com.pythian:site=blog,type=views,target=post1 #CassandraSummit 2014

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JMX Domains org.apache.cassandra. ● db ● internal ● net ● request #CassandraSummit 2014

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JMX Beans org.apache.cassandra.metrics ● db ● internal ● net ● request #CassandraSummit 2014

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JMX org.apache.cassandra.metrics :type= ● Cache ● Client ● ClientRequest ● ClientRequestMetrics ● ColumnFamily ● CommitLog ● Compaction #CassandraSummit 2014 ● DroppedMessage ● FileCache ● Keyspace ● Storage ● ThreadPools

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JMX org.apache.cassandra.metrics type=*,scope=*, name=*, type=ThreadPools, path=*, scope=*, name=*, type=ColumnFamily, keyspace=*, scope=*, name=*, type=Keyspace, keyspace=*, name=*, #CassandraSummit 2014

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Metrics ● Toolkitcalled metrics for metrics o By Coda Hale @ Yammer ● Easy to use ● Popular #CassandraSummit 2014

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Types of Metrics #CassandraSummit 2014 ● Gauge o instantaneous value ● Counter o number that can be incremented & decremented ● Meter o rate of events over time (1/5/15 min moving avg) ● Histogram o representation of statistical distribution § 50, 75, 95, 98, 99, 99.9 percentile § average, median, min, max, standard deviation ● Timer o rate of events (meter) o histogram of duration

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JMX #CassandraSummit 2014 75th percentile is 683 MICROSECONDS (75% took 683us or less) One minute rate is 13,915 calls per SECOND

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JMX ● Overwhelmingat first ● Hard to tell what they mean without the source ● Moves around a lot ● Fortunately there is nodetool #CassandraSummit 2014

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Nodetool ● JMXcommand line wrapper ● Many options ● Operations and diagnostic procedures ● For reactive analysis o ad hoc, spot checks #CassandraSummit 2014

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Nodetool tpstats nodetooltpstats org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name= {ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks} Pool Name Active Pending Completed Blocked All time blocked ReadStage 0 0 113702 0 0 RequestResponseStage 0 0 0 0 0 MutationStage 0 0 164503 0 0 ... InternalResponseStage 0 0 0 0 0 HintedHandoff 0 0 0 0 0 #CassandraSummit 2014 Message type Dropped RANGE_SLICE 0 READ_REPAIR 0 ... REQUEST_RESPONSE 0 COUNTER_MUTATION 0

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Staged Event DrivenArchitecture ● Decomposes complex event system ● Set of stages (thread pools) ● Queue between each ● Shares a lot of pros cons as SOA #CassandraSummit 2014

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Staged Event DrivenArchitecture #CassandraSummit 2014 ReadStage Threads x32 Client Request RequestResponse Threads ReadRepairStage Threads Messaging Service Node 2 Node 1 Node 1 Node 1 = Task

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Staged Event DrivenArchitecture ● Its easy to overrun the processing capabilities of a stage that is not in the requests feedback loop (i.e. ReadRepairStage). ● No write back pressure #CassandraSummit 2014

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Nodetool tpstats nodetooltpstats org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name= {ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks} Pool Name Active Pending Completed Blocked All time blocked ReadStage 0 0 113702 0 0 RequestResponseStage 0 0 0 0 0 MutationStage 0 0 164503 0 0 ... InternalResponseStage 0 0 0 0 0 HintedHandoff 0 0 0 0 0 Message type Dropped RANGE_SLICE 0 READ_REPAIR 0 ... REQUEST_RESPONSE 0 COUNTER_MUTATION 0 #CassandraSummit 2014 RequestResponse Threads

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Nodetool tpstats nodetooltpstats org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name= {ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks} Pool Name Active Pending Completed Blocked All time blocked ReadStage 0 0 113702 0 0 RequestResponseStage 0 0 0 0 0 MutationStage 0 0 164503 0 0 ... InternalResponseStage 0 0 0 0 0 HintedHandoff 0 0 0 0 0 Message type Dropped RANGE_SLICE 0 READ_REPAIR 0 ... REQUEST_RESPONSE 1 COUNTER_MUTATION 0 #CassandraSummit 2014 RequestResponse Threads

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Nodetool tpstats nodetooltpstats org.apache.cassandra.metrics:type=ThreadPools,path={internal|request|transport},scope={*},name= {ActiveTasks|PendingTasks|CompletedTasks|CurrentlyBlockedTasks|TotalBlockedTasks} More at: http://www.evidencebasedit.com/guide-to-cassandra-thread-pools #CassandraSummit 2014

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Nodetool cfhistograms nodetoolcfhistograms {keyspace} {table} org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table} SSTables per Read 1 sstables: 98554 2 sstables: 4534 #CassandraSummit 2014 Write Latency (microseconds) No Data Read Latency (microseconds) 10 us: 2 12 us: 17 14 us: 96 17 us: 208 20 us: 677 24 us: 3081 29 us: 4552 35 us: 3559

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Read Write Pathmile high overview Memtable SSTable #CassandraSummit 2014 Writes Reads

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Nodetool cfhistograms nodetoolcfhistograms {keyspace} {table} org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table} SSTables per Read 1 sstables: 98554 2 sstables: 4534 #CassandraSummit 2014 Write Latency (microseconds) No Data Read Latency (microseconds) 10 us: 2 12 us: 17 14 us: 96 17 us: 208 20 us: 677 24 us: 3081 29 us: 4552 35 us: 3559

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Nodetool cfhistograms 1.1 nodetool cfhistograms {keyspace} {table} org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table} Offset SSTables Write Latency Read Latency Row Size Column Count 1 3579 0 0 0 0 2 0 0 0 0 0 . . . 35 0 0 0 0 0 42 0 0 27 0 0 50 0 0 187 0 0 60 0 10 460 0 0 72 0 200 689 0 0 86 0 663 552 0 0 103 0 796 367 0 0 124 0 297 736 0 0 149 0 265 243 0 0 179 0 460 263 0 0 . . . 25109160 0 0 0 0 0 #CassandraSummit 2014

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Nodetool cfhistograms #CassandraSummit2014 https://gist.github.com/clohfink/6068003

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Nodetool cfhistograms 2.1 nodetool cfhistograms {keyspace} {table} org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table} Keyspace/Table histograms Percentile SSTables Write Latency Read Latency Partition Size Cell Count (micros) (micros) (bytes) 50% 1.00 10.00 524.00 310 5 75% 1.00 11.75 888.00 310 5 95% 1.00 15.00 4843.75 310 5 98% 1.00 17.00 9658.90 310 5 99% 1.00 19.00 12306.47 310 5 Min 0.00 0.00 68.00 30 0 Max 2.00 1219386.00 45383.00 310 5 #CassandraSummit 2014

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Nodetool cfstats nodetoolcfstats {-i} {keyspace}.{table} org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table} Keyspace: Keyspace1 Read Count: 11207 Read Latency: 0.047931114482020164 ms. Write Count: 17598 Write Latency: 0.053502954881236506 ms. Pending Tasks: 0 Table: Standard1 SSTable count: 3 Space used (live), bytes: 9088955 Space used (total), bytes: 9088955 Space used by snapshots (total), bytes: 0 SSTable Compression Ratio: 0.3672150946 Memtable cell count: 0 Memtable data size, bytes: 0 Memtable switch count: 3 Local read count: 11207 Local read latency: 0.048 ms Local write count: 17598 Local write latency: 0.054 ms Pending tasks: 0 Bloom filter false positives: 0 Bloom filter false ratio: 0.00000 Bloom filter space used, bytes: 11688 Compacted partition minimum bytes: 1110 Compacted partition maximum bytes: 126934 Compacted partition mean bytes: 2730 Average live cells per slice: 0.0 Average tombstones per slice: 0.0 #CassandraSummit 2014

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Nodetool cfstats nodetoolcfstats {-i} {keyspace}.{table} org.apache.cassandra.metrics:type=ColumnFamily,keyspace={keyspace},scope={table} Keyspace: Keyspace1 Read Count: 11207 Read Latency: 0.047931114482020164 ms. Write Count: 17598 Write Latency: 0.053502954881236506 ms. Pending Tasks: 0 Table: Standard1 SSTable count: 3 SSTables in each level: [14/4, 1, 0, …, 0] Space used (live), bytes: 9088955 Space used (total), bytes: 9088955 Space used by snapshots (total), bytes: 0 SSTable Compression Ratio: 0.3672150946 Memtable cell count: 0 Memtable data size, bytes: 0 Memtable switch count: 3 Local read count: 11207 Local read latency: 0.048 ms Local write count: 17598 Local write latency: 0.054 ms Pending tasks: 0 Bloom filter false positives: 0 Bloom filter false ratio: 0.00000 Bloom filter space used, bytes: 11688 Compacted partition minimum bytes: 1110 Compacted partition maximum bytes: 126934 Compacted partition mean bytes: 2730 Average live cells per slice: 0.0 Average tombstones per slice: 0.0 #CassandraSummit 2014

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Nodetool proxyhistograms nodetoolproxyhistograms org.apache.cassandra.metrics:type=ClientRequest,scope={Read|Write|RangeSlice},name=Latency #CassandraSummit 2014 $ nodetool proxyhistograms proxy histograms Read Latency (microseconds) 61214 us: 1 Write Latency (microseconds) 103 us: 22 124 us: 142 149 us: 297 179 us: 1190 215 us: 1823 258 us: 2091 ...

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Nodetool compactionstats #CassandraSummit2014 nodetool compactionstats org.apache.cassandra.metrics:type=Compaction pending tasks: 1 compaction type keyspace table completed total unit Progress Compaction Keyspace1 Standard1 6076415 29605054 bytes 20.06% Active compaction remaining time : 0h00m03s

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Nodetool Much more!! http://www.datastax.com/documentation/ cassandra/2.0/cassandra/tools/ toolsNodetool_r.html #CassandraSummit 2014

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OpsCenter ● Providesvisibility to key metrics ● Alarming ● Basic orchestration and config management ● Constantly improving ● Free* ● Almost zero barrier to get setup ● Very few reasons not to run it #CassandraSummit 2014

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OpsCenter ● Homogeneoustooling with rest of stack o Integrate metrics in with what app is using o orchestration and config management ● (paid version) “Good enough” o a mature environment should have more #CassandraSummit 2014

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Reporting Interface DefaultAddons Community JMX Ganglia Cassandra StatsD NewRelic Splunk Console Graphite Cloudwatch Kafka Riemann TempDB Csv Munin Riak InfluxDB Sematext Slf4j MongoDB OpenTSDB Librato … MORE #CassandraSummit 2014

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Reporting Interface ●Configurable with yaml o console, csv, ganglia, graphite ● Create reporter with premain agent o compiling new jar with manifest o add to classpath o add javaagent in cassandra-env.sh #CassandraSummit 2014

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Garbage Collection ●Death, Taxes, and a stop the world GC ● Common issue to all JVM based applications #CassandraSummit 2014

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Garbage Collection Enablegc logging ● Virtually no overhead ● Can be very helpful in diagnosing performance issues #CassandraSummit 2014

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Garbage Collection JVM_OPTS="$JVM_OPTS-XX:+PrintGCDetails" JVM_OPTS="$JVM_OPTS -XX:+PrintGCDateStamps" JVM_OPTS="$JVM_OPTS -XX:+PrintHeapAtGC" JVM_OPTS="$JVM_OPTS -XX:+PrintTenuringDistribution" JVM_OPTS="$JVM_OPTS -XX:+PrintGCApplicationStoppedTime" JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure" JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1" JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log" JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc.log" JVM_OPTS="$JVM_OPTS -XX:+UseGCLogFileRotation" JVM_OPTS="$JVM_OPTS -XX:NumberOfGCLogFiles=10" JVM_OPTS="$JVM_OPTS -XX:GCLogFileSize=10M" #CassandraSummit 2014

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Garbage Collection JVM_OPTS="$JVM_OPTS-XX:+PrintGCDetails" JVM_OPTS="$JVM_OPTS -XX:+PrintGCDateStamps" JVM_OPTS="$JVM_OPTS -XX:+PrintHeapAtGC" JVM_OPTS="$JVM_OPTS -XX:+PrintTenuringDistribution" JVM_OPTS="$JVM_OPTS -XX:+PrintGCApplicationStoppedTime" JVM_OPTS="$JVM_OPTS -XX:+PrintPromotionFailure" JVM_OPTS="$JVM_OPTS -XX:PrintFLSStatistics=1" JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc-`date +%s`.log" JVM_OPTS="$JVM_OPTS -Xloggc:/var/log/cassandra/gc.log" JVM_OPTS="$JVM_OPTS -XX:+UseGCLogFileRotation" JVM_OPTS="$JVM_OPTS -XX:NumberOfGCLogFiles=10" JVM_OPTS="$JVM_OPTS -XX:GCLogFileSize=10M" #CassandraSummit 2014

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Garbage Collection Couldbe its own talk Honorable mentions: ● https://github.com/chewiebug/GCViewer ● http://jworks.idv.tw/GcWeb/ ● Python, R, Octave #CassandraSummit 2014

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Logging /var/log/cassandra/system.log oprovides a rolling log o log4j /var/log/cassandra/output.log o captured standard error and standard out o truncated on restart #CassandraSummit 2014 System Logs o syslog, dmesg, etc

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OS Metrics #CassandraSummit2014 Shout-out: http://www.brendangregg.com/linuxperf.html

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JVM #CassandraSummit 2014 ● Heap o GC logs o JMX ● Threads o jvmtop o Jstack (+htop) o kill -3 o JMX

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And Everything #CassandraSummit2014

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Questions ? #CassandraSummit2014

Cassandra Summit 2014: Monitor Everything!

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